Polypropylene synergistically nucleated by a novel β-nucleating and foaming nucleating agent: foaming performance and material properties

A novel beta-nucleating and foaming nucleating agent (HQ[6]/EA) of polypropylene (PP) was synthesized by hemicucurbit[6]uril (HQ[6]) complexed with ethanedioic acid (EA) through the solution method. HQ[6] and EA bonded together through non-covalent bond force, and the morphology changed obviously. The maximum content of beta-PP crystal form was 15.34% with 0.5% (by weight) HQ[6]/EA, and the crystallization rate and crystallinity of the nucleated PP were improved, and the decomposition temperature of PP composites was 50 celcius higher than that of pure PP. During the injection molding process of nucleated PP foaming material, HQ[6]/EA was employed as the nucleating agent and azodicarbonamide as the foaming agent. While HQ[6]/EA was added with 0.5% (by weight), the average cell size of the foamed composite was reduced by about two times relative to that of pure PP, and the cell density was increased by about 6.5-fold. The mechanical properties of PP composited with HQ[6] and HQ[6]/EA with the loading from 0.25% to 5.0% (by weight) were examined. Among the different nucleating agents studied, HQ[6]/EA with a loading of 0.5% (by weight) exhibited a considerable improvement in the mechanical properties after comparison with pure PP. The overall enhancement of tensile properties for PP composites increased by 32.2%, the flexural strength properties increased dramatically by about 12.7%, and the impact strength increased by more than two times.

Automated summary

A novel beta-nucleating and foaming nucleating agent HQ[6]/EA was synthesized for polypropylene (PP), which significantly improved the crystallization rate, crystallinity, and mechanical properties of nucleated PP. When used as a nucleating agent, HQ[6]/EA showed reduced cell size and increased cell density in the foamed PP composite. The addition of HQ[6]/EA at 0.5% (by weight) exhibited considerable enhancement in tensile, flexural strength, and impact strength properties of PP composites.